7. Sherlock's Knowledge Of London
Towards the climax of the episode John and Sherlock chase a taxi through the streets of London. They are someway behind the taxi when they begin their chase but by the end they have managed to catch up with it. In this scene, we get to see Sherlock's mind laid out on a map of London. The alternate routes of the taxi and the two men, is mapped out as an overlay to images of John and Sherlock running after the car. This serves to show us Sherlock's incredible memory as well as his encyclopaedic knowledge of the streets of London. Both of these traits are integral to the character of Sherlock and so this scene becomes an integral piece of character development. The theme of Sherlock's knowledge of London is revisited time and again throughout the show and this is where it all begins.